Liu Shenping, Mansour Mahmoud N, Dillman Keith S, Perez Jose R, Danley Dennis E, Aeed Paul A, Simons Samuel P, Lemotte Peter K, Menniti Frank S
Pfizer Global Research and Development, Pfizer Inc., Eastern Point Road, Groton, CT 06340, USA.
Proc Natl Acad Sci U S A. 2008 Sep 9;105(36):13309-14. doi: 10.1073/pnas.0708850105. Epub 2008 Aug 29.
The phosphodiesterases (PDEs) are metal ion-dependent enzymes that regulate cellular signaling by metabolic inactivation of the ubiquitous second messengers cAMP and cGMP. In this role, the PDEs are involved in many biological and metabolic processes and are proven targets of successful drugs for the treatments of a wide range of diseases. However, because of the rapidity of the hydrolysis reaction, an experimental knowledge of the enzymatic mechanisms of the PDEs at the atomic level is still lacking. Here, we report the structures of reaction intermediates accumulated at the reaction steady state in PDE9/crystal and preserved by freeze-trapping. These structures reveal the catalytic process of a PDE and explain the substrate specificity of PDE9 in an actual reaction and the cation requirements of PDEs in general.
磷酸二酯酶(PDEs)是金属离子依赖性酶,通过对普遍存在的第二信使环磷酸腺苷(cAMP)和环磷酸鸟苷(cGMP)进行代谢失活来调节细胞信号传导。在这一过程中,磷酸二酯酶参与许多生物和代谢过程,并且已被证实是治疗多种疾病的成功药物的作用靶点。然而,由于水解反应速度很快,目前仍缺乏关于磷酸二酯酶在原子水平上的酶促机制的实验性认识。在此,我们报告了在PDE9/晶体中反应稳态下积累并通过冷冻捕获保存的反应中间体的结构。这些结构揭示了磷酸二酯酶的催化过程,并解释了PDE9在实际反应中的底物特异性以及一般情况下磷酸二酯酶对阳离子的需求。